Question

Tests for ammonia, where a colour change is involved?
A) Nessler’s solution gives a distinct yellow colouration with ammonia.
B) With \[{\text{HCl}}\] gas giving white fumes of ammonia chloride.
C) When mixed with oxygen it burns with a pale yellow green flame.
D) all of the above.

Answer 1

Hint: Arrhenius is one of the concepts for acid and bases. Swedish chemist Arrhenius is the world's first chemist to talk about acid and bases. Depending on his concept and limitation later so many concepts are developed. Even Arrhenius is the birthplace of the concept of acids and bases. Followed by Arrhenius chemist the concept of acids and bases discuss Bronsted and Lowry in the world.

Complete answer:
The molecular formula of ammonia is \[{\text{N}}{{\text{H}}_{\text{3}}}\].
The Nessler’s solution is\[{\text{[}}{{\text{K}}_{\text{2}}}{\text{(Hg}}{{\text{I}}_4}{\text{)]}}\].
Nessler’s solution giving a distinct yellow colouration with ammonia, Nessler’s test is
\[{\text{2[}}{{\text{K}}_{\text{2}}}{\text{(Hg}}{{\text{I}}_4}{\text{)] + 3KOH + N}}{{\text{H}}_{\text{3}}} \to {\text{[H}}{{\text{g}}_{\text{2}}}{\text{O}}{\text{.N}}{{\text{H}}_{\text{2}}}{\text{]I + 7KI + 2}}{{\text{H}}_{\text{2}}}{\text{O}}\]
Hence, tests for ammonia, where a colour change is involved, Nessler's solution giving a distinct yellow colouration with ammonia.
Ammonia react with\[{\text{HCl}}\], the reaction is given below,
 \[{\text{HCl + N}}{{\text{H}}_{\text{3}}} \to {\text{N}}{{\text{H}}_{\text{4}}}{\text{Cl}}\]
Hence, tests for ammonia, where a colour change is involved with \[{\text{HCl}}\]gas giving white fumes of ammonia chloride.
Oxygen it burns with a pale yellow green flame.
\[{\text{4N}}{{\text{H}}_{\text{3}}}{\text{ + 3}}{{\text{O}}_{\text{2}}} \to {\text{2N}}{}_{\text{2}}{\text{ + 6}}{{\text{H}}_{\text{2}}}{\text{O}}\]
Tests for ammonia, where a colour change is involved when mixed with oxygen it burns with a pale yellow green flame.
According to the above discussion option A, B and C come the right answer.

Hence, option D is correct, because all of the above tests for ammonia colour change is involved.

Note:
In generally, pH value of all acids are in between \[{\text{0}}{\text{.9}}\]-\[6.9\] and all the bases are in between\[7.1 - 14.0\]. But, Arrhenius theory has some limitations. One of the main limitations is not being able to explain the behaviour of acids and bases in non-aqueous solvents such as acetone etc,. It is not able to explain the acid which doesn't contain hydrogen and bases don’t contain hydroxyl ion in the formula. Ammonia is a well known base and is not accepted as base in Arrhenius base. These limitations are recovered by further coming theories like the Bronsted and Lowry concept of acids and bases.